Method of continuously producing metal wire and profiles

ABSTRACT

METAL WIRE AND PROFILES ARE CONTINUOUSLY MANUFACTURED BY DIPPING A HELICAL SCREW FORMED CORE WIRE INTO A METAL MELT. THE WIRE LEAVES AND PREFERABLY ALSO ENTIRES THE MELT THROUGH ITS UPPER SURFACE.

Aug. 10, 1971 B. o. N. HANSSON ETAI- METHOD OF CONTINUOUSLY PRODUCING METAL WIRE 'AND PROFILES 2 Sheets-Sheet 1 Filed Dec. 9. 1968 FIG.1

FIG.2

0, 1971 B. o. N. HANSSON EI'AL 3,598,639

METHOD OF CONTINUOUSLY PRODUCING METAL WIRE AND PROFILES Filed Dec. 9, 1968 2 Sheets-Sheet 2 s m l 4 A a l. 3 2

m .2) n 2 h h l. 9 1 m m W 6 m 5/ It ww 4 n I 1 United States Patent US. Cl. 117114R Claims ABSTRACT OF THE DISCLOSURE Metal wire and profiles are continuously manufactured by dipping a helical screw formed core wire into a metal melt. The wire leaves and preferably also enters the melt through its upper surface.

It has been suggested to continuously produce metal wire by feeding a cold metal wire through a die in the bottom of a crucible containing hot metal and into that metal. When the cold wire passes the molten metal, that metal will be cooled and freeze onto the core wire. The amount of metal which thus is deposited on the core will depend on the temperatures of the core and melt and also of the coefiicients of heat conductivity, specific heat and melting heat and of the speed of the wire through the melt.

According to a known procedure the core may be die scalped (i.e. die-shaped) treated with a vacuum before it reaches the die and passes into the melt in order to free the core from dross, oxides and gases which, when they meet the melt, will cause porousness in the deposited new metal. It is however not an easy task to achieve continuous troublefree production with those multiple processes (die scalping, evacuation, dipping) as scalping dies and the die at the bottom of the crucible have but limited life and thus both molten metal and air have a tendency to leak into the evacuating chamber.

If, for instance, the core wire is not properly evacuated its surface may contain occluded gas, which expands when it meets the hot melt. Bad adherence and porousness of the deposit may be the result and a leaking die may also cause the melt to pass into the evacuated chamber. This may cause special difficulties if the core wire has not a circular but a shaped cross section.

According to the present invention such difficulties are avoided. The core wire which before reaching the melt has been bent into helical screw shape enters the melt and leaves the melt from its upper surface and thestill screw shaped wire leaves the melt and the crucible in a screw shaped movement to be cooled still being kept in screw shape until the wire with its deposit is so cooled that it may be straightened out, rolled down or otherwise treated.

According to a preferred method the core wire enters the melt from its upper surface.

According to another preferred method both the melt and the core wire are maintained in a vacuum and thus not only the wire but also the metal is degassed before they meet and thus porousness of the deposit is avoided. 7 It should here be emphasized that porousness or bad adherence of the deposit may have several causes:

(1) Gas occluded on the core wire will expand when heated by the melt,

(2) Gas dissolved in the molten metal is less soluble in a colder melt and, thus, is freed when the melt is cooler,

(3) Gas which is developed through a chemical reaction. An example is S0 which may develop from sulphide existing on the surface of the core wire and oxide 3,598,639 Patented Aug. 10, 1971 dissolver in the hot metal, the sulphide and the oxide dissolver forming S0 when core and melt meet.

It is essential for this invention that the gases are free to evolve when core and metal meet. This situation is achieved when the wire enters from the upper surface.

According to another embodiment of the invention also the part of the melt where the wire leaves the melt is kept under a vacuum and thus both melt and deposit are protected from contamination.

In the continued description of the invention reference is made to the drawings.

FIG. 1 shows a method for continuous manufacturing of wire according to the invention, whereby the screw shaped wire enters and leaves the melt from its upper surface.

FIG. 2 shows a preferred method according to which both wire and melt are under a vacuum where the wire enters the melt and the cooling is arranged at a higher pressure than at the entrance where the wire and the melt are degassed.

FIG. 3 shows another embodiment. The dipping is made at vacuum and the cooling and transport of the dipped wire is achieved by means of one transport and one cooling roller.

In FIG. 1 a crucible 1 is shown which through a feed conduit 2 is filled with new metal when deposited metal is taken away from the crucible. From a storage drum 3 core wire 4 is fed to the crucible by means of a feeding device 5 (e.g. rollers) while the core wire 4 is being shaped into helical screw shape. One part of a screw sling 6 is dipping into and moving through the melt in such a way that the wire passes into and out of the melt through its upper surface. All other slings 7 of the metal deposited wire 8 are outside the crucible 1. At one or more of those slings outside the crucible cooling is arranged e.g. by means of dipping into water (not shown). This is followed by straightening of the wire and winding onto a takeup drum 9 as by coiling the wire. The cooling is thus arranged at a distance from-and beside-the crucible whereby such risks as e.g. explosions are avoided. The crucible 1 is by means of a wall 10 divided into two communicating compartments, one for feeding with new metal and one for dipping. The wall 10 is meant for skimming off dross. Thus, straightening of the wire before it is cooled and risky cooling of the wire above the molten metal is avoided.

Thanks to the helical screw shape of the wire it may be inserted into the melt from its upper surface and evacuation for degassing of the wire and the melt is not necessary as the gases will to a large extent be blown away when the heat from the melt causes them to expand and be blown away.

If alternativelyaccording to a prior art method-the core wire enters through a die in the bottom of the crucible such gases may be encapsulated by the deposited metal and cause porousness and bad adherence between core and metal.

According to the method shown in FIG. 2 both metal and wire are evacuated and degassed. The dipping takes place in a crucible 11 which is divided into one degassing chamber 12 and one cooling chamber 13 by means of a wall 14. That wall is immersed into the melt 15 and divides the crucible into two communicating parts. The pressure in the degassing part may be very low (e.g. mm. Hg) and higher than in the cooling part (e.g. 100-400 mm. Hg).

The screw shaped core wire 4 is fed through the die 16 into the evacuating chamber and enters the melt at a high vacuum leaving it at the cooling side 13 at a lower vacuum after having passed below the dividing wall 14. When the wire has been cooled at one or more of the slings 7 the metal deposited wire 8 may be straightened and taken to the outside of the container 11 through a packing 17. When the core wire has received its cover of deposited metal it may have an outside diameter of varying dimension. Thanks to the fact that the wire is cold and the vacuum not too high it is possible to use resilient rubber sealing means (at the cooling side) as used when continuously vulcanizing rubber cables. At that vulcanizing process the cable passes into and out of a pipe containing 20 atmospheres hot steam. Several sealing means behind each other (labyrinth sealing means) may also be used.

While more and more wire is fed through the machine metal will disappear from the crucible and new metal must be continuously degassed. Due to the vacuum this is achieved by means of a pipette action through a pipe 18 which is immersed in a melting kettle 19. Thanks to the vacuum this is automatically achieved and the metal is also automatically degassed as the crucible 1 has such shape that a relatively large surface of metal is continuously exposed to the vacuum before it arrives at the place of dipping.

As the pressure in the cooling part 13 can be kept higher than in the vacuum part 12 the demand on tightness of the sealing means 17 is not high. The sealing means 17 may be omitted if the pressure in part 13 is 760 mm. Hg. The difference in height between the two metal surfaces on both sides of wall 14 however then may be too large and the time during which the wire is maintained in the molten metal too long. The fact that the absolute vacuum which may be needed for degassing some metals is not needed on the cooling side also has another advantage. If the pressure in the cooling part was very low the metal melt 15 might evaporate and then perhaps condense onto the cooling means, e.g. cooling rollers.

-In FIG. 3 is shown how the cooling may be achieved. Dipping and cooling is made in a container 11 in which the dipping crucible 1 is encased. The crucible 1 is divided in a degassing part 20 and a dipping part 21 by means of a wall 10 which ends at a distance from the bottom of the crucible 1. Thanks to the vacuum maintained in container 11 the level of molten metal is automatically kept constant as new metal is sucked up from a melt storage kettle 19 at exactly the same rate as metal freezes onto the core wire 4. The core wire 4 enters the container 11 through a die 16. A feeding device shapes the wire in helical screw shape and the wire maintains its helical shape through the dipping procedure and then moves along an internally cooled cooling roll 22 against which it is pressed by a pressure roller 23. The cooled wire 8 maintains its screw shape until it leaves the roller 22 and the container 11 through a die 17 The core wire may not only have circular cross section but as Well be a fiat tape or have any of a variety of cross-sectional shapes or outlines, as resilient sealing means may be used both where the core wire enters and the manufactured product leaves the container 11.

What we claim is:

1. Method for continuous manufacturing of metal profiles by dipping a cold metallic core strip into a metal melt held in a dipping crucible comprising the steps of forming the core strip into a helical screw shape, passing said core strip through said melt and onto a, cooling means in a helical path, said core strip entering and a coated core strip leaving said melt through an upper surface portion of said melt, and maintaining said helical screw shape until said coated core strip has been cooled.

2. Method according to claim 1 including the further step of treating the melt and the core strip with a vacuum as the core strip is being introduced into the upper surface portion of the melt.

3. Method according to claim 2 comprising the further step of treating the upper surface portion of the metal melt and the coated core strip with a vacuum when the coated core strip is leaving the upper surface portion of the melt.

4. Method according to claim 2 comprising the further step of maintaining a higher vacuum pressure in the area where the core strip enters the melt than in the area where the core strip leaves the melt, and effecting said higher and lower vacuum pressures by means of a partition wall dividing the dipping crucible into two communicating parts.

5. Method according to claim 4 comprising the further steps of continuously feeding the melt into the dipping crucible through a pipette immersed into a storage crucible, and maintaining a vacuum pressure above the upper melt surface in the dipping crucible which is lower than a pressure maintained above the upper melt surface in the storage crucible.

6. Method according to claim 1 comprising the further step of rolling the coated core strip on a cooling cylinder after said core strip has left the dipping crucible to transport the coated core strip from the crucible and to cool the coated core strip.

7. Method for continuously coating a metal melt on a cold core wire by dipping the cold core wire into the metal melt held in a dipping crucible comprising the steps of forming the core wire into a helical screw shape, passing said core wire through said melt and on towards a cooling means in a helical path, the wire entering and leaving the melt through an upper surface of the melt, and maintaining said helical screw shape until said wire has been cooled.

8. Method according to claim 7 including the further steps of partitioning said dipping crucible containing said metallic melt into a degassing chamber communicating via a lower portion of said dipping crucible with a cooling chamber, maintaining a high vacuum pressure above the melt in said degassing chamber and maintaining a lower vacuum pressure above the melt in the cooling chamber.

9. Method according to claim 7 including the further steps of partitioning said dipping crucible into a degassing portion communicating via a lower portion of said dipping crucible with a dipping portion, maintaining a vacuum pressure above the surface of the melt in the degassing portion and the dipping portion, said wire entering the melt through the upper surface of the melt in the degassing portion and leaving the melt through the upper surface of the melt in the dipping portion, and continuously supplying metallic melt to the dipping crucible via a pipette immersed in a storage crucible, and maintaining a high vacuum pressure above the melt surface in the storage crucible and a lower vacuum pressure above the melt surface in the dipping crucible.

10. Method according to claim 9 including the further step of rolling the wire on a cooling cylinder to transport the wire from the clipping crucible to a windup and to cool the wire.

References Cited UNITED STATES PATENTS 182,468 9/ 1876 Paine 117l14X 1,343,842 6/1920 Piersol 1171 19 1,933,401 10/1933 Ward 117119.2X 2,405,221 8/ 1946 Mann 1171 19X 2,495,695 1/1950 Carnin et al. 118(W&C Imm U) 2,926,103 2/1960 Brick 117119.2X 2,996,410 8/1961 Hnilicka, Jr. 117-119X 3,130,068 4/1964 Whitley 1l7-114(A)X 3,145,119 8/1964 Laforce et al 1171 19.2X 3,392,0551 7/1968 Martin et al. 1171 14X ALFRED L. LEAVITT, Primary Examiner J. R. BATTEN, Jr. Assistant Examiner U.S. Cl. X.R.

117115. 119, 119.2, 128; ll844, 50, 69, 420, Dig. l9 

